This invention relates to a wire tension control apparatus especially adapted for use in coil winding machines and, in particular, armature and stator winding machines. As will become apparent, the apparatus of this invention is capable of being used wherever variations in wire tension are encountered.
Several types of unreeling or dereeling devices have been proposed and used. In general, these devices are mounted closely adjacent to a spool of wire and are designed to exert some tension on the wire. They are also typically provided with some means for leveling out the tension depending upon the demands of the machine with which the wire is to be used. A typical prior device is shown in U.S. Pat. No. 2,643,075 granted to K. A. Moore on June 23, 1953. The device shown in the above mentioned patent is adequate for many coil winding applications including armature winding machines and stator winding machines. However, higher speed winding machines require more complete control of the tension on the wire than can be provided by the device shown in the above patent. In the case of high speed stator winding machines, it is desirable also to include a powered wire takeup device which operates in synchronism with the winding shuttle, such a takeup device being shown in U.S. Pat. No. 3,251,559 granted to H. W. Moore on May 17, 1966. In general, the wire takeup device shown in the latter patent draws wire from the dereeler when the winding head is not drawing wire and then releases the wire it draws when the winding head is drawing wire so that there is a more uniform demand for wire from the dereeler. The apparatus shown in the latter patent has been successfully used on stator winding machines having shuttle spindles which operate in the range of 800 or 900 complete strokes per minute.
More recently, stator winding machines having shuttle speeds operating in the range of 1000 to 1250 or more complete strokes per minute are being developed, and it has been discovered that a combination of a dereeling device such as shown in the above mentioned K. A. Moore U.S. Pat. No. 2,643,075 and the powered wire takeup device shown in the H. W. Moore U.S. Pat. No. 3,251,559 do not adequately control the wire tension. As a result, the wire exiting from the winding head will tend to balloon outwardly instead of closely following the guide surfaces which are provided for the wire. The wound coils have loosely formed turns and wire breakage may occur.